Tropism and pathogenesis of the avian influenza A/H7N9 virus in ex vivo andin vitro cultures of the human respiratory tract and human airway organoids Kenrie P.Y. Hui1, Denise I.T. Kuok1, Christine H.T. Bui1, Ka-chun Ng1, Chris K.P. Mok2,3, Zi-feng Yang3, Wenda Guan3, Leo L.M. Poon1, Nanshan Zhong3, Yi Guan1, Hans Clevers4, J.S. Malik Peiris1, John M. Nicholls5*, Michael C.W. Chan1*
1School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China; 2The HKU-Pasteur Research Pole, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China; 3State Key Laboratory of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; 4Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Utrecht, Netherlands; 5Department of Pathology, Queen Mary Hospital, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China. *Corresponding Authors
Influenza A/H7N9 virus has caused six epidemics in China since 2013. In 2017, previously low pathogenic avian influenza (LPAI) H7N9 virus underwent mutation in its haemagglutinin to give a highly pathogenic avian influenza (HPAI) virus, which causes 32 human cases and potentially poses human and animal health threats. We compared the tropism and cytokine induction of HPAI H7N9 with LPAI H7N9, HPAI H5N1 and 2009 pandemic H1N1 (H1N1pdm) viruses in human bronchus and lung explant cultures, human alveolar epithelial cells (AECs) and pulmonary microvascular endothelial cells (HMVEC-L). Besides, we used a novel platform—human airway organoids, to assess the tropism and replication competence of H7N9 virus and other avian influenza strains.
Replication kinetics of HPAI and LPAI H7N9 were comparable in ex vivo cultures of human bronchus and lung. HPAI H7N9 predominantly infected type-II alveolar epithelial cells in the lung, while limited infection was observed in the bronchus. HPAI H7N9 and H5N1 replicated to significantly higher titers than LPAI H7N9 and H1N1pdm in AECs and HMVEC-L. HPAI H5N1 virus was a more potent inducer of the mRNA expression of IFN-, IL-6, IFN-λ1, RANTES than HPAI and LPAI H7N9 viruses. Comparable results were observed in tropism and virus replication competence between ex vivo cultures of human bronchus and human airway organoids.
Our study highlights the efficient replication of HPAI H7N9 virus in ex vivo cultures of human bronchus and lung and a higher replication competence in AECs and HMVEC-L than some other LPAI H7N9 viruses implying the potential for HPAI H7N9 virus to disseminate beyond the respiratory tract. In addition, human airway organoid cultures provide an alternative physiologically relevant model to assess the pandemic threat of animal influenza viruses.
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